Method and apparatus for providing logical combination of N alpha operations within a graphics system

Abstract

A graphics system including a custom graphics and audio processor produces exciting 2D and 3D graphics and surround sound. The system includes a graphics and audio processor including a 3D graphics pipeline and an audio digital signal processor. Logical combination of N alpha compares can be used to provide a wide range of imaging effects including but not limited to cartoon outlining.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Application Nos. 60 / 226,915 and 60 / 226,888 filed Aug. 23, 2000, the entire contents of which are hereby incorporated by reference. This application is related to concurrently-filed application Ser. No. 09 / 722,367 of Drebin et al entitled “Recirculating Shade Tree Blender For a Graphics System”.FIELD OF THE INVENTION[0002]The present invention relates to computer graphics, and more particularly to interactive graphics systems such as home video game platforms. Still more particularly, this invention relates to the use of logical combination of N alpha channel operations to generate interesting visual graphics effects including but not limited to non-photorealistic images such as cartoon outlining.BACKGROUND AND SUMMARY OF THE INVENTION[0003]Many of us have seen films containing remarkably realistic dinosaurs, aliens, animated toys and other fanciful creatures. Such animations are made...

AI Technical Summary

Benefits of technology

[0005]Most computer graphics research has tended to focus on producing realistic images. This research has been very successful. Computers can now generate images that are so realistic that you can't tell them apart from photographs. For example, many of us have seen very convincing dinosaurs, aliens and other photorealistic computer-generated special effects in movie and television. New pilots train on computer-based flight simulators so realistic that they nearly duplicate actual flying. Low-cost home video game systems can now provide a remarkable degree of realism, giving the game player an illusion of driving a real race car along a track, skiing down a snow and ice covered ski slope, walking through a medieval castle, or the like. For most games, this illusion of realism significantly enhances the game play experience.

[0014]The combination of alpha compares and alpha logical operations can be used for a wide range of additional alpha-based effects. For example, dual alpha comparisons can be used to provide non-photorealistic effects such as cartoon outlining (e.g., to efficiently determine whether to blend a cartoon outline color based on said logical combination by implementing an absolute value function).

Problems solved by technology

Because computer graphics generation is complex, computer-generated three-dimensional graphics just a few years ago were mostly limited to expensive specialized flight simulators, high-end graphics workstations and supercomputers.

The public saw some of the images generated by these computer systems in movies and expensive television advertisements, but most of us couldn't actually interact with the computers doing the graphics generation.

An issue that arises when implementing various complex alpha comparisons including but not limited to the cartoon outlining algorithm mentioned above, is how to efficiently perform more complicated alpha comparisons in hardware using a single rendering pass.

Such an arbitrarily complex alpha test capability has not generally been available in the past within the context of a low cost graphics system such as a home video game or a personal computer graphics card.

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